矩形区组方“RBS”设计及其在树木育种中的应用Ⅰ.单个“RBS”设计统计分析

本文介绍矩形区组方"RBS"设计的基本方法,单个"RBS"设计方差分析的数学模型,处理平均数效应,期望均方分解,遗传力及其遗传变异系数估值,并举例介绍"RBS"在树木育种中的应用。     

湖北省高等院校干道绿化和广场绿化建设的探讨

科学进行干道和广场的绿化规划与树种选择 ,对全面提升校园景观质量具有重要的意义。结合当前湖北地区部分高校干道绿化和校园广场绿化建设中存在的一些问题 ,介绍了干道和广场的绿化规划和树种选择原则 ,并详细探讨了适合湖北地区高校种植的干道绿化树种和广场绿化植物。     

Customer adapted grading of Scots pine sawn timber using a multivariate method

To define new grading rules, or to customize the ones in use in a rule-based automatic grading (RBAG) system of boards, is a time-consuming job for a sawmill engineer. This has the effect that changes are rarely made. The objective of this study was to continue the development of a method that replaces the calibration of grading rule settings by a holistic-subjective automatic grading, using multivariate models. The objective was also to investigate if this approach can improve sawmill profitability and at the same time have a satisfied customer. For the study, 323 Scots pine (Pinus sylvestris L.) boards were manually graded according to the preferences of an important customer. That is, a customer that regularly purchases significant volumes of sawn timber. This manual grading was seen as reference grading in this work. The same boards were also scanned and graded by a RBAG system, calibrated for the same customer. Multivariate models for prediction of board grade based on aggregated knot variables, obtained from the scanning, were calibrated using partial least squares regression. The results show that prediction of board grades by the multivariate models were more correct, with respect to the manual grading, than the grading by the RBAG system. The prediction of board grades based on multivariate models resulted in 76–87% of the boards graded correctly, according to the manual grading, while the corresponding number was 63% for the RBAG system.     

运用数量化方法估测普洱县森林蓄积量

根据普洱县森林遥感调查资料 ,利用卫星影像特征判读数据与地面实测数据建立数学类型 ,估测森林蓄积量。首先将 2 0 0块有、疏林地数据输入数据本中 ,然后分析其与优势树种、龄组、郁闭度、海拔、坡向、坡度的关系 ,结果把样地分为针叶林、阔叶林、针阔混交林三个类型分别建立数学模型 ,以估测每公顷蓄积量。数学模型的建立是根据数量化模型的原理来编程 ,并通过计算机的不断调试 ,直到可行为止。蓄积量比较精度达到 90 3%。     

硬岩抗剪强度参数的最优化确定法

为了减小岩工程分析计算的工作量和节约研究经费,须利用有限的室内实验样本的测定值,通过对有限实验样本数据的回归分析整理,确定岩石抗剪强度参数c、φ,进而估计岩体的抗剪强度c、φ.由于试验方法、试验条件等有一定局限性,因而,岩石力学参数的试验结果具有一定的不确定性.其不确定性包含随机性和模糊性.而用传统的数理统计方法处理岩石样本值,显然是不合适的,只有通过寻求最优的数学回归分析方法,来处理相关试验结果.笔者通过对硬岩变角度剪切实验和常规三轴压缩实验的数据回归分析,得到利用最小二乘法的抛物线回归分析结果和随机-模糊回归分析结果比较符合.因而,为了优化计算结果而又避免繁琐的计算,通常可以采用最小二乘法的抛物线回归分析计算代替随机-模糊回归分析相关结果.     

城市广场复层结构绿化比例分析评价——以南京市城市广场为例

根据陈自新等专家提出的城市绿地乔、灌、草配植的适宜比例建议方案,将其数值范围按比例扩大化后分为三类评价类型,对南京市19个已经建成的城市广场的复层结构绿化比例进行了单项分析和综合分析评价。根据城市广场的特殊性和三类评价类型的绿化景观丰富度、舒适度和满意度进行实地调查,提出了复层结构绿化的适宜比例、基本适宜比例和不适宜比例,提出了复层结构绿化比例范围扩大化、增加单体灌木色块种植和城市行道树按比例计量的建议。     

Height–diameter equations for boreal tree species in Ontario using a mixed-effects modeling approach

Height–diameter relationships based on stand characteristics (trees/ha, basal area, and dominant stand height) were investigated for balsam fir, balsam poplar, black spruce, jack pine, red pine, trembling aspen, white birch, and white spruce using data from permanent growth study plots in northern Ontario, Canada. Approximately half the data were used to estimate model parameters with the rest used for model evaluation. Multiple Chapman–Richards functions with parameters expressed in terms of various stand characteristics were fit to determine the best models for predicting height.     

寒地城市广场设计计划

作者对北方寒冷城市的广场设计问题进行了分析研究,并提出了一些观点和想法,对北方城市广场的设计问题提出一些新的思路。     

从能量原理推导J积分的表达式

本文用最小位能原理和最小余能原理，推导出了弹塑性断裂力学中的Ｊ积分表达式．并由此而得到非线性弹性材料和弹塑性材料的平面裂纹尖端发生断裂前，位能与众能同时达到最小值．这一推导，为能量原理在断裂力学中的应用提出了一个新的见解．